1. Field of the Invention
The present invention relates to a viewfinder having a zooming function. The present invention also relates to a camera having such viewfinder.
2. Description of the Prior Art
In many conventional cameras capable of zooming, the cam for zooming held on the finder unit is driven by being interlocked with a zoom drive system in the lens barrel of the taking lens or the lens barrel itself by use of gears or the like. In recent years, a camera has been put on the market in which zooming of the viewfinder is performed by driving the zoom cam held on the lens barrel of the taking lens by interlocking it with an axially movable barrel of the lens barrel.
However, the former structure is disadvantageous in cost and size reduction of the camera because a mechanical member for the interlocking such as a gear is necessary. In addition, a deviation is caused between the zooming of the lens barrel of the taking lens and the zooming of the viewfinder because of a backlash in the mechanical member, so that the magnification of the viewfinder deviates for the actually taken image.
In the latter structure in which the zooming of the viewfinder is carried out by the zoom cam on the taking lens barrel, since the accuracy of the lens units of the viewfinder are dependent on the assembly condition other than the viewfinder, the error of the relative position becomes large, and this incurs degrading of the performance. Since the zoom cam is not integrated in the finder unit until the finder unit is combined with the taking lens barrel, it is impossible to confirm the function and performance of the finder unit alone during camera manufacturing. In addition, since the cam follower for the zoom cam to be provided on the finder unit is mounted when the entire camera is assembled, the assembly is difficult.